Electric hammer



Dec. 3, 1929. R. RIGGS ELECTRIC HAMMER Filed Nov. 1. 1927 INVENTOR ATTO R N EY WITNESS:

Patented Dec. 3, 1929 ROY RIGGS, OF BEDIEORI), INDIANA ELECTRIC HAMMER Application filed November 1, 1927. Serial N'o. 230,308.

This invention relates to an electric hammer which is mainly designed for carving stone and the like, the general object of the invention being to provide an electric motor for driving the hammer carrying member and also to provide means for adjusting the force of the blows delivered to the chisel so that such blows can be regulated according to the work being done.

Another object of the invention is to pro vide one or more fans on the motor shaft for furnishing air to cool the motor and also to provide an air blast for blowing dust and the like oil the stone being carved.

This invention also consists in certain other features of construction and in the combination and arrangement of the several parts, to be hereinafter fully described, illustrated in the accompanying drawings and so specifically pointed out in the appended claim.

In describing my invention in detail, reference will be had to the accompanying drawings wherein like characters denote like 25 or corresponding parts throughout the several views, and in which Figure 1 is an elevation of the device.

Figure 2 is a bottom plan view.

Figure 3 is a section on line 33 of Fig so are 2.

Figure 4 is a section on line as. of Figure 3.

In these views, 1 indicates the body of the hammer which has its end portions offset in opposite directions from the central portion, as clearly shown in Figure 2. This body is formed with the chamber 2 at its rear end, the circular chamber 3 at its center and the passage 1 in its front part which to communicates with the chamber 3 and passes through the front end of the body.

An electric motor 5 is located in the chamher 2 and its shaft 6 is suitably journaled in the body and passes through the upper pori5 tion of the chamber o. A worm 7 is con nected with the part of the shaft located in the chamber 3. A transverse shaft 8 is arranged in the chamber 3 and carries a worm gear 9 which meshes with the worm 7. A

so fly wheel 10 is also attached to the shaft 8 and carries a plurality of hammers 11 which may be removably fastened to the fly wheel so that new hammers may be substituted for the old ones when the old ones become worn.

A bushing 12 is arranged in the passage t and this bushing is provided with an internal flange 13. A spring plunger 1 1 is arranged in the rear part of the bushing and has its stem passing through the opening formed by the flange 13 so that said stem can engage the shank of the chisel 14 which is adapted to be placed in the outer end of the bushing. The coil spring 15 of the plunger tends to hold the same in its rearward position and against an adjustable stop which consists of a bar 16 slidably mounted on the top of the body and held in place by the guide 1.7, the front end of the bar being bent twice at right angles and projecting through a slot 18 formed in the top of the body, into the chamber 3. As will be seen, the front end of the bar 16 forms a stop for limiting the rear movement of the plunger. A number of holes 19 is formed in the top of the body, any one of which is adapted to be engaged by a pin 20 on the rear end of the bar 16 so that by placing this pin in the proper hole, the bar 16 will be held in the desired position.

From the foregoing it will be seen that when current is supplied to the motor, the

worm on its shaft, engaging the worm gear on shaft 8, will rotate said shaft 8 and thus the hammer carrying wheel will also be rotated. As the wheel revolves, the hammers will strike the rear end of the plunger, forc ing the plunger forwardly against the action of its spring and thus imparting blows to the chisel to cause the same to penetrate the stone or other object being worked upon. By adjusting the rear limit of movement of the plunger, through means of the stop, the force of the blows of the hammers, delivered to the chisel by the plunger, can be controlled, as will be understood from an inspection of Figure 3. Thus the operator can adjust the hiindle so as to cause it to deliver light blows to the chisel or heavy blows, according to the work to be done.

Fans 21 are fastened to that part of the motor shaft within the chamber 2, these fans acting to keep the motor cool and also to fur- V nish an air blast through the passages 22 and the nipple 23 for blowing dust from the 5 stone being carved.

A cap 24 covers the rear end of the body so that access can be had to the motor and a detachable plate 25 covers one end of the chamber 3 so that access can be had to the hammer carrying member and the parts in said chamber. 7

This improved hammer will reduce vibrations to a minimum so that the operator is not subjected to the discomforts of holding a'hammer which vibrates with considerable'force, such as a pneumatic hammer, nor one in which the air exhaust is so great as to cause discomfort to the operator, as in a, pneumatic hammer.

It is thought from the foregoing description that the advantages and novel features of my invention will be readily apparent.

It is to be understood that I may make changes in the construction and in the combination and arrangement of the several parts, provided that such changes fall within the scope of the appended claim.

What I claim is An electric hammer comprising a casing 3O hELVlIlg a centrally arranged circular part forming a chamber, a cylindrical part at I one end thereof and a bored part at its other end, an electric motor in the cylindrical part, a shaft connected therewith passing into the chamber in the circular part, a transversely arranged shaft in the circular part, gearing connecting the shafts together, a hammer carrying member on the transverse shaft, the bore in the bored part having its inner end 40 tangentially arranged with respect to the chamber, a spring plunger in the bore with its inner end projecting into the chamber so that said end will be struck by the hammers, a bar slidably mounted on the casing and having a part projecting into the chamber for engaging the inner end of the plunger to limit the inward movement of the plunger and means for holding the bar in adjusted position. V In testimony whereof I affix my signature.

ROY RIGGS. 

